"Assisted Living" follows 21-year-old Todd through his final day of work as a janitor at a nursing home. Todd smokes pot frequently on the job, which allows him to enjoy the surreal environment of the assisted living facility. He also breaks the monotony of his days with entertaining—and extremely unprofessional—diversions involving the residents: he rides through the halls in borrowed wheelchairs; he plays pool and Scrabble with them; he even "plays God" on the telephone, giving residents the illusion of speaking to their departed loved ones in heaven. But however much these activities cheer the seniors, Todd's behavior angers the staff and undermines the policies of the home.

It is ultimately Todd's interactions with Mrs. Pearlman—a statuesque resident who longs for a visit from her son—that jeopardize his job. Mrs. Pearlman, who is in the early stages of Alzheimer's, has difficulty distinguishing the real world from her memories of it. As her odd friendship with Todd develops, she begins to mistake the janitor for her son. When Todd in turn begins to assume the role, he rediscovers his own humanity and instigates a transformation for them both.